Snow cover distribution as mapped from satellite photography

Utilizing data from three winter seasons, snow cover distributions in the relatively flat terrain of the Missouri and Upper Mississippi River basins are mapped from satellite photography. Techniques are developed for identifying snow cover and for differentiating between snow and cloud. Comparisons between snow data observed by satellites and snow data conventionally acquired indicate that, in almost all cases, snow can be distinguished from cloud on the bases of current cloud reports, pattern continuity, landmark identification, and texture. Snow cover can be mapped from Tiros or Essa resolution photography with an accuracy of approximately ±20 miles, often providing a more detailed mapping than can be obtained from conventional station networks. Qualitative estimates of snow depth can also be obtained from satellite photography. In nonforested areas, reflectivity increases with snow depth, until an accumulation of about 4 to 6 inches is reached ; after that, the reflectivity remains unchanged. In forested areas, no discernible relationship between reflectivity and snow depth is observed.